The present invention relates to an operating control device for an air conditioner for use in a vehicle wherein when a load applied to an engine increases while a driving on an ascending hill or road surface, the device is operative so as to allow a compressor for the air conditioner to be inoperative to maintain sufficient vehicle drive performance.
Heretofore, in vehicles in which an air conditioner is provided, particularly in diesel engine driven vehicles, a control system is provided to halt or interrupt the air conditioning operation when a heavy load on the engine is detected during its run on an acsending road surface, because of a reduction in the driving performance of the vehicle with the air conditioner being operated in a cooling mode.
It has been known to provide for the air conditioner with an operating control device comprising an electromagnetic relay connected to a compressor and a negative pressure detector which renders the relay turned off so as to lessen the load applied to the engine due to the operation of the compressor, when an accelerator pedal is depressed due to driving on an ascending road surface and thus the negative pressure at an intake manifold decreases.
However, with the conventional device in which decrease of a negative pressure in the intake manifold is detected, even when a vehicle accelerates during run on a flat or level road surface in which an inoperative condition of the compressor is not required, there is a possibility that the operation of the compressor is interrupted due to a decrease in the negative pressure of the engine, resulting in the problem that the cooling capacity is lowered.
Further, another prior art device is also known, in which the operation of the compressor is halted when an increase in the engine load is detected through a rise in the cooling water temperature. However, with this device, since it is likely to have a time delay in the rise of the water temperature with respect to an increase in the engine load, it is impossible to stop the operation of the compressor unless the hill climbing run continues for more than certain time, thus resulting in the problem that a time delay cannot be avoided in the compressor interruption control.